Remove iPhone passcode without restoring

I have an iPhone 6 on iOS 9 that I forgot the passcode to. The phone is not stolen, it is clean IMEI and it has no iCloud lock. The phone is not logged into iCloud so I cannot wipe it like that. I've had this phone since it came out and I lost it a while back and I just recently found it. I just need some help if anyone knows how to get rid of the passcode lock without updating to the latest iOS version because I want to keep it on iOS 9. I don't mind losing everything on it, just if I can get access to the phone without updating to latest iOS version. Please, any help would be great.